Evaluation of molecular diagnostic approaches for the detection of BRAF p.V600E mutations in papillary thyroid cancer: Clinical implications.

Abstract

Differentiated papillary thyroid cancer (PTC) is the most common cancer of the endocrine system. PTC has a very good prognosis and a high 5 year survival rate; however, some patients are unresponsive to treatment, and their diagnosis eventually results in death. Recent efforts have focused on searching for prognostic and predictive factors that may enable treatment personalization and monitoring across the course of the disease. The presence of the BRAF mutation is considered to contribute to the risk of poor clinical course, according to American Thyroid Association (ATA) recommendations. The method used for genotyping can impact the predicted mutation frequency; however, ATA recommendations do not address this issue. We evaluated the molecular diagnostic (BRAF p.V600E mutation) results of 410 patients treated for PTC. We thoroughly analyzed the impact of three different BRAF mutation detection methods, Sanger Sequencing (Seq), allele-specific amplification PCR (ASA-PCR), and quantitative PCR (qPCR), on the frequency of mutation detection in 399 patients. Using Seq, we detected the BRAF mutation in 37% of patients; however, we were able to detect BRAF mutations in 57% and 60% of patients using the more sensitive ASA-PCR and qPCR technologies, respectively. Differences between methods were particularly marked in the thyroid papillary microcarcinoma group; BRAF p.V600E mutations were found in 37% of patients using Seq and 63% and 66% of patients using ASA-PCR and qPCR, respectively. We also evaluated how these different diagnostic methods were impacted by DNA quality. Applying methods with different sensitivities to the detection of BRAF p.V600E mutations may result in different results for the same patient; such data can influence stratification of patients into different risk groups, leading to alteration of treatment and follow-up schemes.